While part-time employment among youth is becoming increasingly prevalent, there has been little systematic study of its antecedents or its consequences for adolescent well-being, mental health, and achievement. Most prior research is based on cross- sectional data, making it impossible to separate the causal impacts of work from selection effects. A cohort of 1,000 youth will be studied over a 4-year period from grades 9 to 12. This cohort will be randomly sample from students enrolled in the St. Paul public schools. Indicators of well-being, mental health, and work-related orientations preceding initial experiences in the workforce will be examined as predictors of adolescent work orientation and behavior. The influence of the family on adolescent work outcomes will a)so be assessed. The dimensions of adolescent work to be studied include the temporal aspects of employment (hours spent working, the duration and continuity of work over time), work autonomy, the complexity and repetitiveness of job tasks, and the amount and quality of contact with adults and peers or the job. The implications of the timing of employment--whether work experiences have different consequences depending on the maturity of the person--will also be examined. The following indicators of mental health and adjustment are conceptualized as potential antecedents and consequences of work experiences: the self-concept (including the academic self-concept, self-esteem, and efficacy); orientations to work; depressed mood; and school achievement. We will also examine the effects of employment on the adolescent's relationships with family members and peers, and on attitudes and behaviors in school. Finally, we will investigate the possibility that the effects of work are conditional on the developmental status of the adolescent (as indicated by age and psychological attributes), gender, ethnicity, and circumstances in the family and school. Understanding these conditional relationships is necessary for the development of an informed social policy concerning the employment of youth.